The kinetics of stacking reactions in nucleic acids and simple model systems will be studied to determine the driving force behind the interaction. A laser temperature-jump instrument capable of measuring nanosecond relaxations will be used for these experiments. Concurrently, the structures of nucleic acids will be investigated by means of circular dichroism, fluorescence detected circular dichroism, and kinetics of oligomer binding, and single strand unstacking. In particular, the structures of the anticondon loop in yeast phenylalanine tRNA and E. coli initiator tRNA, and of the CCA terminus in yeast initiator tRNA will be studied. The above techniques will also be applied to explore protein-nucleic acid interactions.